Any of several related peptide hormones that affect skin coloration and, in mammals, also play a role in regulating hunger and metabolism. MSHs are produced from the precursor pro-opiomelanocortin (POMC) and secreted by the anterior or (when present) the intermediate lobe of the pituitary gland. In humans, certain neurons in the arcuate nucleus of the hypothalamus release α‎-MSH, which is a potent suppressor of appetite and has a key role in regulating energy balance; it acts antagonistically to neuropeptide Y and has potential as an antiobesity agent. α‎-MSH acts also as an anti-inflammatory cytokine and as a neuropeptide in the brain. It stimulates sexual activity, is involved in regulation of heart rate and blood pressure, and promotes tanning in people with fair skin by stimulating pigment cells (melanocytes) to produce melanin. In amphibians, fishes, and reptiles, MSH controls the dispersal of melanin in chromatophores of the skin, causing the skin to darken.